Osteoarthritis is a debilitating disease of cartilage tissue characterized by joint pain and stiffness. A promising technique to noninvasively monitor the progression of this disease is 23Na MRI. 23Na images taken of the patellar articular cartilage of a healthy volunteer show a SNR>20. In these images, the articular cartilage has an intensity ~3x greater than that of skin and surrounding muscle. Fat and bone marrow of the patella are not visible. In an in-vitro model of degradation, half of a bovine patellar cartilage was degraded in a trypsin bath while half was left undegraded and served as a control. These images show a significant decrease in the sodium signal on the degraded vs. the non-degraded halves, demonstrating that sodium imaging can monitor changes in cartilage tissue. By using different concentrations of trypsin solution, it is possible to show that the extent of degradation can be monitored using 23Na MRI. Further studies on human subjects are in progress.